I was looking for the maximum routing table capacity supported on ISR 4331 with default 4gb memory. I was unable to find any documents relevant on cisco's site. Would really appreciate any links or documents on this.
since the routing table is not the only thing that uses memory, there is no clear cut answer. It depends on what else you have configured (e.g. NAT uses up memory). What specific requirements do you have for your IP routing ? Are you running BGP ?